Title: Gear modification to reduce by-catch in Tanzania shrimp fishery

Type:
Final project
Year of publication:
2005
Publisher:
UNU-FTP
Place of publication:
Reykjavík
Number of pages:
30
Supervisors: Einar Hreinsson

Abstract

There has been a need to improve the selectivity for shrimp and fish in tropical shrimp fisheries areas like Tanzania to reduce by-catch in coastal fisheries. The reduction of juvenile shrimp and fish can constitute a strategy to minimise discard. A study was done to review the literature and to evaluate possible solutions for the Tanzanian shrimp fishery.

In this report, modified fishing gear with a selection grid and a square cod end is proposed which could improve the selection and reduce by-catch. The selection grid is made from aluminium mounted at an angle of 33° in the net section and has a length and width of 1.65 m and 0.8 m respectively, with bars 14 mm apart. Mesh size for the square mesh cod end was chosen 45 mm.

A full scale prototype of the selection grid and square mesh cod end was constructed. The proposed function of a designed grid system is that larger shrimp and larger fish are guided into the cod end, and that small shrimp and juvenile fish will escape through the sorting grid. The use of square mesh cod end gives an additional opportunity for juveniles to escape. 

Documents and links